Many types of key bolts are known in the art including the above discussed type wherein a locking key is movable in a transversely arranged aperture in the bolt shank. However, most of the prior art key bolts with such a locking key are of the automatic locking type generally embodying some arrangement of spring means, for automatically urging the locking key laterally of the shank of the bolt. U.S. Pat. No. 1,925,174 issued on Sept. 5, 1933 To W. F. Cremean discloses one type of selflocking key bolt. U.S. Pat. No. 2,297,831 issued Oct. 6, 1942 to A. S. Heard discloses another type of automatically locking key bolt, and U.S. Pat. No. 2,361,491 dated Oct. 31, 1944 likewise discloses an automatically locking key bolt.
Applicant's own U.S. Pat. Nos. 3,476,007, 3,673,910 and 3,861,267 disclose key bolts of the type wherein a locking key is disposed in a slot at the end of the bolt shank, which receives the key therein, with the key being rotatable 90.degree. from an unlocking position where it is disposed generally parallel to the axis of the bolt shank, to a locking position where it is disposed perpendicular to the bolt shank.